tests: Introduce running tests with GNU autotest in OpenBSC

The quality of the tests is of different value but it is good to
get started and improve from here.
diff --git a/openbsc/tests/mgcp/Makefile.am b/openbsc/tests/mgcp/Makefile.am
index 472368c..ff67cf8 100644
--- a/openbsc/tests/mgcp/Makefile.am
+++ b/openbsc/tests/mgcp/Makefile.am
@@ -2,6 +2,8 @@
 AM_CFLAGS=-Wall -ggdb3 $(LIBOSMOCORE_CFLAGS) $(LIBOSMOSCCP_CFLAGS) $(COVERAGE_CFLAGS)
 AM_LDFLAGS = $(COVERAGE_LDFLAGS)
 
+EXTRA_DIST = mgcp_test.ok
+
 noinst_PROGRAMS = mgcp_test
 
 mgcp_test_SOURCES = mgcp_test.c